Twenty healthy men subjects will be recruited as subjects for this study. Subjects should be generally healthy, with no history of blood donation in the last 6 months, should weigh less than 85 Kg, and not take iron supplements and/or multivitamin supplements. Subjects should have familiarity to sports and running, but not currently (i.e. in the past 3 months) training for more than 1h per week on average.